Fig. 4. Expression of ECM molecules on neurospheres. (A) Laminin 2 chain (red) is highly expressed at the edge of neurospheres. Nuclei are counterstained with DAPI (green). (B) A model of the neurosphere three-dimensional structure, summarizing the data presented and showing how nestin, EGF receptor (EGFR), ß1 integrin (ß) and laminin 2 (L2) are found in the same region. Note that, for clarity, the GFAP distributed throughout the centre of the sphere is only shown on the left side of the model, whereas the nestin and BrdU labelling around the perimeter of the entire sphere is only shown on the right side. (C,D) In the sectioned neurospheres laminin 1 is found in the center (C), whereas laminin 2 predominates at the edge (A,D). Scale bar: 20 µm.